1. Field of the Invention
The present invention relates to a continuously variable speed transmission mechanism or constant velocity joint (CVJ), and more particularly an improved one continuously variable speed transmission mechanism in which the input shaft and the output shaft are positioned coaxially and reactive forces of input and output disks are received by a common thrust bearing.
2. Related Background Art
In a toroidal type continuously variable speed transmission mechanism, power rollers are positioned between an input disk and an output disk and are moved in a plane perpendicular to the axis of said disks, in order to vary the effective radii of contact points of said input and output disks with the power rollers, whereby the input power can be transmitted with continuous variation of speed to the output side. At the power transmission, the input disk is pressed to the power rollers, and the input and output disks receive reactive forces from the power rollers. How to receive said reactive forces is an issue even related to the entire structure of the continuously variable speed transmission mechanism.
As a conventional example, FIG. 6 illustrates a continuously variable speed transmission mechanism disclosed in the Japanese Utility Model Laid-open Application No. 63-30656.
Referring to FIG. 6, on a shaft 100 there are rotatably mounted an input disk 102 and an output disk 104, between which provided are power rollers 106. By the function of loading rollers 110 based on the rotation of a loading cam 108, the input disk 102 is pressed to the power rollers 106, whereby the rotating power of the input disk is transmitted through the power rollers 106 to the output disk 104. Said power is transmitted to a gear 114 fixed on an output shaft 112 positioned parallel to the input shaft 100, and is taken out from said output shaft 112.
The reactive force to the right, applied to the input disk 102 at the power transmission, is transmitted through the loading rollers 110, loading cam 108 and input shaft 100 and is received by an inner ring 117 of a bearing 116 supporting said input shaft 100. On the other hand, the reactive force to the left, applied to the output disk 104, is transmitted by an extension 117 thereof and is received by an inner ring 121 of a bearing 120. As the above-mentioned bearings are in mutual contact across a stop ring therebetween, said reactive forces are received and are not transmitted to the outside. However, since the output power is finally taken out from the output shaft 112 provided parallel to the input shaft 100, there is required two shafts which increases not only the entire dimension of the transmission but also the weight and manufacturing cost thereof. The drawback in such conventional technology originates from a fact that the input shaft 100 extends through the tubular extension 117 of the output disk 104 (with the input shaft inside and the output shaft outside), so that the output power cannot be obtained directly from such outside shaft but has to be obtained from the output shaft 112 through the gear 112.
Also in the conventional continuously variable speed transmission mechanism shown in FIG. 6, a housing 130 is provided, in a portion close to the left-hand end of the shaft 100, with an oil path 126 communicating with a lubricating oil supply device (not shown). Also at the left-hand end of the shaft 100 and corresponding to the oil path 126, there is provided an axially extending oil supply path 127, and an oil supply path 128 is so formed as to connect the internal end of the oil supply path 127 and the external periphery of the shaft 100. Said oil supply path 128 is positioned in a space defined between the bearings 116 and 120.
The bearing 116 supporting the shaft 100 and the bearing 120 supporting the output disk 104 are lubricated by the lubricating oil supplied from said oil path 126. The revolutions of the shaft 100 and the output disk 104 are respectively equal to those of the inner ring of the bearing 116 and that of the bearing 120. As the oil supply path 126 is formed on the shaft 100, the lubricating oil is tangentially discharged with the speed of the shaft 100, namely that of the inner ring of the bearing 116. Consequently, said lubricating oil does not generate resistance to the rotation of the bearing 116. On the other hand, since the output disk 104 rotates with a different speed from that of the shaft 100 except the case of a speed transmission ratio of 1 : 1, the lubricating oil discharged from the oil supply path 128 generates a resistance (agitating resistance) to the rotation of the bearing 120, corresponding to the speed difference. Such resistance is one of the causes deteriorating the efficiency of the transmission. Furthermore, the bearings 116 and 120 are positioned along the axial direction, thus extending the axial dimension. Such axially extended dimension has posed a problem in the installation of such continuously variable speed transmission mechanism.